Most paved thoroughfares overlie water lines, sewer lines and conduit systems for the distribution of electricity, gas, steam, and/or communications. Access to these below-surface facilities is usually provided by a vertical opening which is capped by a cover or grate that is level with the top of the thoroughfare. The cover or grate usually rests upon a supporting framework. The supporting framework is either embedded in the paved thoroughfare or rests on a foundation either in or below the paved thoroughfare.
When it becomes necessary to resurface this thoroughfare a layer of new material, usually asphalt, is simply applied to the top of the old thoroughfare. The cover or grate must then be raised to correspond to the new surface level. In the past this raising has been achieved by either digging up the supporting framework and re-embedding it (which is expensive in terms of labor and creates definite safety hazards or by placing some sort of an elevating device between the embedded framework and the cover (which often involves a number of structural problems and other limitations and in particular the inability of such extensions to be used along with the existing cover or grate when the new surface level is less than the thickness of the cover or the grate plus approximately 1/2 inch).
For a long time the art has needed a new method and/or apparatus which will permit such covers or grates to be elevated without digging up the support frames and without the height limitations inherent in prior art extensions.